If I was to make a holder, it would be exactly like the Aloris #4D, boring bar holder with split clamping.
Tool Post Grinder
- Thread starter Susquatch
- Start date
Yes, I considered that. But notice how the spindle motor is already very close to the lathe center.
To get some adjustment range, and still have the motor rigidly held, I had planned to hang the motor over the end of the compound taking advantage of the way a tool holder normally mounts.
I have some "glorious" plans for that grinder. They are probably all beyond its capability but a fellow must dream. If even 20% of those plans get realized, the grinder will see a lot of use. So I'd also really like to retain the quick change feature.
ThirtyOneDriver
Johnathan (John)
I have a 60° end mill cutter that you can borrow @Susquatch.
That sounds like a plan @ThirtyOneDriver ! I don't think I need one for anything else so borrowing one makes sense. If I break it, I'll replace it!
Tom Kitta
Ultra Member
Yes it's 500w. Feels like plenty of power. I need to play around with the spindle assembly and see what results I get. The 12000 rpm speed will be good for small internal stones while I need to run much slower for 3in stones.
That was my thinking too.
My spindle motor arrived a bit ago, but first I need to make a holder to fit my bxa quick change tool post. I already have an aluminium block to make it from. But I'm fussy so there is fair bit of planning and fabrication to do before I can actually run it.
Where do you get high quality (ie safe) well balanced 3" stones? And are they marked with a safe rpm for them?
I haven't looked at the 3" wheel you referenced yet. But your question about ER11 collet is appropriate. I had assumed everyone was talking a 1/4" shaft designed to fit a motor with a 1/4" shaft holder of some kind. I was picturing a wheel somewhat like a cutoff blade just a bit thicker - say 1/4". But maybe I am not gunna be able to do outside grinding after all. Or perhaps only with a smaller stone held on an angle.
It's a good question. How would you answer it yourself?
Why don't you want to modifying the holder that came with the motor?
You have no idea how hard I tried to make that work. In the end, I simply gave up. The original doesn't have enough meat to take the dovetail and the through bolts end up interfering with the compound table. Lastly, a two part assembly would be difficult to assemble. An entirely new holder doesn't need bolts and can accommodate the dovetail.
The bigger question is can I make a dovetail that fits my tool post well enough to handle the spindle motor.
Tom Kitta
Ultra Member
I do not use ER11 I use ER20.
Tom Kitta
Ultra Member
You have no idea how hard I tried to make that work. In the end, I simply gave up. The original doesn't have enough meat to take the dovetail and the through bolts end up interfering with the compound table. Lastly, a two part assembly would be difficult to assemble. An entirely new holder doesn't need bolts and can accommodate the dovetail.
The bigger question is can I make a dovetail that fits my tool post well enough to handle the spindle motor.
I should show you my design. No issues - used original aluminium. Less work. Just make it square and add an adapter plate to the bottom. The whole thing is very rigid. It is held with 3/8 bolt against T-nut.
Basically I machined T-nut - simple - right?
I machined the original clamp square so its even. I measured how much higher it needs to be then my spindle - about 5.5mm. I machined adapter plate of 5.5mm. I added adapter plate to the bottom via 4 tiny cap screws - I think size 10-24. The 3/8 just holds the adapter plate against T-nut. Works great. Very rigid. Maybe I would not lift the whole lathe by it but I am sure it will work for the grind stones.
Tom Kitta
Ultra Member
I got some cheap Chinese wheels and norton wheels.
I have these bad boys:
PACK OF 5 NEW!!! NORTON SG RECESSED GRINDING WHEELS 3" X 1-1/4" X 5/8" 5SG46-KVS | eBay
Recessed Grinding Wheels.
www.ebay.com
I also have like 10 cup wheels in case someone wants them - good stuff, norton as well. I don't think I need 10 identical ones. https://www.ebay.com/itm/353890612374
Not sure what is the RPM max. I assume 5500 or 6000 would be safe limit.
Tom Kitta
Ultra Member
I have 500w spindle with ER20 on her. You don't have to use supplied ER11.
I might take you up on cup wheel. I need to figure out adaptability to my bench grinder. Is 1.25 the hole ID I assume?
NORTON ALUNDUM CUP GRINDING WHEELS 4"/3" X 1-1/2" X 1-1/4"
Tom, how is the ER collet holder attached to the shaft (like key or set screw on flat or?).
How are you varying RPM on that motor? I guess I'm more wondering what happens to 500W rating when you go to 40% throttle or whatever?
Do you happen to know what it has for bearings or just give it a go?
How are you varying RPM on that motor? I guess I'm more wondering what happens to 500W rating when you go to 40% throttle or whatever?
Do you happen to know what it has for bearings or just give it a go?
Tom Kitta
Ultra Member
Yes, 1 1/4 is I think standard for SG. You can always use adapter - my TC&G is 1 in and I have some adapters to use same wheels as on SG.
Tom Kitta
Ultra Member
Collet is attached via two set screws. Its a DC motor and you simply lower the voltage to get speed down. I do not think it will be a big deal, these grinders are usually not too powerful - I mean 6" pedestal grinders are usually 250w and they move two 6" stones doing far more cutting action then 3" or similar stone.
Tom Kitta
Ultra Member
Yes the ER11 chuck was like .1mm smaller then the spindle. Same with the ER20. I could not have put them on, it was not even close to interference fit. So I reamed 8mm. Not sure whatever that was a great idea - I guess I see soon.